Conventional processes for etching high-k gate dielectric layers apply anisotropic plasma etch and isotropic wet etch techniques. Dry etch processes may damage the substrate that lies beneath the high-k gate dielectric, if they etch the substrate at a significantly faster rate than they etch the dielectric. Although wet etch processes may etch the dielectric selective to the underlying substrate, such processes may etch the dielectric where it is located beneath the gate electrode, which may weaken or lift that structure.
Accordingly, there is a need for an improved process for making a semiconductor device that includes a high-k gate dielectric. There is a need for such a process that etches the exposed part of the high-k film selective to the underlying substrate and selective to the part of that film that the gate electrode covers. The method of the present invention provides such a process.